Hotspot Size-Dependent Thermal Boundary Conductance in Nondiffusive Heat Conduction

2015 ◽  
Vol 137 (8) ◽  
Author(s):  
Yanbao Ma
Keyword(s):  
Thermal Transport ◽  
Critical Role ◽  
Nonlocal Effects ◽  
Thermal Boundary Conductance ◽  
Interfacial Conditions ◽  
Size Dependent ◽  
Transfer Processes ◽  
Thermal Energy Conversion ◽  
Theoretical Predictions ◽  
The Time Domain

Thermal transport across interfaces can play a critical role in nanosystems for thermal management and thermal energy conversion. Here, we show the dependence of the thermal boundary conductance (G) of the interface between a 70-nm Al transducer and a Si substrate on the size of a laser pump diameter (D) in the time-domain thermoreflectance (TDTR) experiments at room temperature. For D ≥ 30 μm, G approaches to a constant where diffusion dominates the heat transfer processes. When D decreases from 30 μm to 3.65 μm, G decreases from 240 to 170 MW/m2K due to the increasing nonlocal effects from nondiffusive heat transport. This finding is vital to our understanding of the thermal boundary conductance: it depends not only on inherent interfacial conditions but also on external heating conditions, which makes the accurate measurements and theoretical predictions of thermal transport across interfaces in micro/nanosystems more challenging.

scholarly journals Electro-thermal transport in disordered nanostructures: a modeling perspective

2020 ◽  
Vol 2 (7) ◽  
pp. 2648-2667
Author(s):  
Fabian Ducry ◽  
Jan Aeschlimann ◽  
Mathieu Luisier
Keyword(s):  
Molecular Dynamics ◽  
Quantum Transport ◽  
Thermal Transport ◽  
Thermal Effects ◽  
Critical Role ◽  
Random Access ◽  
Shed Light

We review here how molecular dynamics and quantum transport can be combined to shed light on the performance of, for example, conductive bridging random access memories, and we show that electro-thermal effects play a critical role.

Grain-Size-Dependent Thermal Transport Properties in Nanocrystalline Yttria-Stabilized Zirconia

2001 ◽  
Vol 703 ◽  
Author(s):  
Ho-Soon Yang ◽  
J.A. Eastman ◽  
L.J. Thompson ◽  
G.-R. Bai
Keyword(s):  
Grain Boundaries ◽  
Thermal Transport ◽  
Chemical Vapor ◽  
Yttria Stabilized Zirconia ◽  
Organic Chemical ◽  
Stabilized Zirconia ◽  
Size Dependent ◽  
Metal Organic ◽  
Organic Chemical Vapor Deposition

ABSTRACTUnderstanding the role of grain boundaries in controlling heat flow is critical to the success of many envisioned applications of nanocrystalline materials. This study focuses on the effect of grain boundaries on thermal transport behavior in nanocrystalline yttria-stabilized zirconia (YSZ) coatings prepared by metal-organic chemical vapor deposition.

Thermal boundary conductance between Al films and GaN nanowires investigated with molecular dynamics

2014 ◽  
Vol 16 (20) ◽  
pp. 9403-9410 ◽  
Author(s):  
Xiao-wang Zhou ◽  
Reese E. Jones ◽  
Patrick E. Hopkins ◽  
Thomas E. Beechem
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulations ◽  
Thermal Transport ◽  
Thermal Boundary Conductance ◽  
Gan Nanowires ◽  
System P ◽  
Dynamics Simulations ◽  
Important System

Using molecular dynamics simulations, we studied the thermal boundary conductance between GaN nanowires and Al films and showed how it may be possible to enhance interfacial thermal transport in this important system.

Experimental Study of the Plastic Interaction of Model Surface Asperities during Sliding

1968 ◽  
Vol 10 (2) ◽  
pp. 121-132 ◽  
Author(s):  
C. M. Edwards ◽  
J. Halling
Keyword(s):  
Experimental Study ◽  
Friction And Wear ◽  
Normal Force ◽  
Tangential Force ◽  
Experimental Results ◽  
Interfacial Conditions ◽  
High Adhesion ◽  
Theoretical Predictions ◽  
Very High ◽  
Low Shear

The paper describes an experimental study of the plastic interaction of triangular shaped lead model asperities deformed under conditions of plane strain. The investigation yields values of the normal and tangential force variations throughout the junction interaction and details of the plastic deformation particularly in relation to junction growth. A number of asperity interfacial conditions are considered ranging from complete adhesion to very low shear strengths achieved using p.t.f.e. strip. The experimental results are compared with an earlier theoretical solution to this problem and show reasonable agreement with the theoretical predictions. In particular it is shown that the normal force, which is usually compressive, may become tensile for conditions of high adhesion between the asperities. This leads to very high values of the macroscopic friction coefficient such as occur in hard vacuum situations. The experimental results for the various surface conditions show sufficient agreement with theoretical predictions to justify the use of this type of theoretical approach for the wider study of the friction and wear of mating surfaces.

scholarly journals Parsimonious Network Based on a Fuzzy Inference System (PANFIS) for Time Series Feature Prediction of Low Speed Slew Bearing Prognosis

2018 ◽  
Vol 8 (12) ◽  
pp. 2656 ◽  
Author(s):  
Wahyu Caesarendra ◽  
Mahardhika Pratama ◽  
Buyung Kosasih ◽  
Tegoeh Tjahjowidodo ◽  
Adam Glowacz
Keyword(s):  
Fuzzy Inference System ◽  
Fuzzy Inference ◽  
Predictive Analytics ◽  
Critical Role ◽  
Inference System ◽  
Low Speed ◽  
Vibration Data ◽  
Machine Failure ◽  
The Time Domain ◽  
Parsimonious Network

In recent years, the utilization of rotating parts, e.g., bearings and gears, has been continuously supporting the manufacturing line to produce a consistent output quality. Due to their critical role, the breakdown of these components might significantly impact the production rate. Prognosis, which is an approach that predicts the machine failure, has attracted significant interest in the last few decades. In this paper, the prognostic approaches are described briefly and advanced predictive analytics, namely a parsimonious network based on a fuzzy inference system (PANFIS), is proposed and tested for low speed slew bearing data. PANFIS differs itself from conventional prognostic approaches, supporting online lifelong prognostics without the requirement of a retraining or reconfiguration phase. The PANFIS method is applied to normal-to-failure bearing vibration data collected for 139 days to predict the time-domain features of vibration slew bearing signals. The performance of the proposed method is compared to some established methods, such as ANFIS, eTS, and Simp_eTS. From the results, it is suggested that PANFIS offers an outstanding performance compared to those methods.

scholarly journals Size-dependent phononic thermal transport in low-dimensional nanomaterials

2020 ◽  
Vol 860 ◽  
pp. 1-26 ◽  
Author(s):  
Zhongwei Zhang ◽  
Yulou Ouyang ◽  
Yuan Cheng ◽  
Jie Chen ◽  
Nianbei Li ◽  
...  
Keyword(s):  
Thermal Transport ◽  
Size Dependent ◽  
Low Dimensional

Size-dependent mode contributions to the thermal transport of suspended and supported graphene

2019 ◽  
Vol 115 (12) ◽  
pp. 123105 ◽  
Author(s):  
Ji-Hang Zou ◽  
Xin-Tong Xu ◽  
Bing-Yang Cao
Keyword(s):  
Thermal Transport ◽  
Size Dependent

Anharmonic Phonon Interactions at Interfaces and Contributions to Thermal Boundary Conductance

2011 ◽  
Vol 133 (6) ◽  
Author(s):  
Patrick E. Hopkins ◽  
John C. Duda ◽  
Pamela M. Norris
Keyword(s):  
Inelastic Scattering ◽  
Thermal Transport ◽  
Phonon Scattering ◽  
Transmission Model ◽  
Material Interfaces ◽  
Physical Consideration ◽  
New Model ◽  
Thermal Boundary Conductance ◽  
Anharmonic Coupling ◽  
Scattering Events

Continued reduction in characteristic dimensions in nanosystems has given rise to increasing importance of material interfaces on the overall system performance. With regard to thermal transport, this increases the need for a better fundamental understanding of the processes affecting interfacial thermal transport, as characterized by the thermal boundary conductance. When thermal boundary conductance is driven by phononic scattering events, accurate predictions of interfacial transport must account for anharmonic phononic coupling as this affects the thermal transmission. In this paper, a new model for phononic thermal boundary conductance is developed that takes into account anharmonic coupling, or inelastic scattering events, at the interface between two materials. Previous models for thermal boundary conductance are first reviewed, including the diffuse mismatch model, which only considers elastic phonon scattering events, and earlier attempts to account for inelastic phonon scattering, namely, the maximum transmission model and the higher harmonic inelastic model. A new model is derived, the anharmonic inelastic model, which provides a more physical consideration of the effects of inelastic scattering on thermal boundary conductance. This is accomplished by considering specific ranges of phonon frequency interactions and phonon number density conservation. Thus, this model considers the contributions of anharmonic, inelastically scattered phonons to thermal boundary conductance. This new anharmonic inelastic model shows improved agreement between the thermal boundary conductance predictions and experimental data at the Pb/diamond and Au/diamond interfaces due to its ability to account for the temperature dependent changing phonon population in diamond, which can couple anharmonically with multiple phonons in Pb and Au. We conclude by discussing phonon scattering selection rules at interfaces and the probability of occurrence of these higher order anharmonic interfacial phonon processes quantified in this work.

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